Fuel reformers can be used to convert alcohol fuels into gaseous fuels (reformates) to fuel an engine. For example, an ethanol reformer can reform ethanol into a reformate gas comprising hydrogen (H2), carbon monoxide (CO), and methane (CH4) for combustion in an engine. The fuel reformer reaction may be driven by recovered exhaust heat from the engine and gaseous reformate output by the reformer may be stored, e.g., as a compressed or adsorbed gas, for use by the engine.
The inventors herein have recognized that since reformate output by a fuel reformer may include CO, storage of reformate may be degraded due to the presence of CO with the remaining gasses.
In one example approach, in order to at least partially address the above issues, a method for operating an engine is provided. The method comprises: reforming a fuel into a gaseous fuel comprising H2, CO, and CH4; and selectively storing at least one or both of H2 and CH4. For example, CO produced by the reformer may be combusted in the engine and/or engine exhaust rather than being stored.
In this way, reformate components produced by a fuel reformer, e.g., H2 and CH4, may be stored and buffered for use by an engine. Such buffering enables more or less of the H2 and CH4 to be delivered to the engine commensurate with operating conditions, without also requiring storage of CO with the H2 and CH4. Rather, the CO may be delivered to the engine without buffering, as its effect in controlling engine operation, such as knock mitigation, etc., is less than that of the remaining reformate gases (H2 and CH4).
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.